Elevator door control mechanism



Oct. 11, 1955 H. E. GALANTY ELEVATOR DOOR CONTROL MECHANISM m 34. .4 E ml Z S W m w? s X 7/ W (a V P u 1 Ml m W \w l n H, W.Z\m W A w WK; W m X/VMn/VZ AWKOLD EDWVFD 640%77 INVE NTQR BY ATTORNEY Oct. 11, 1955 H. E. GALANTY ELEVATOR DOOR CONTROL MECHANISM 5 Sheets-Sheet 3 Filed Nov. 13, 1952 FIQIO BY ATTORNEY United States Patent ELEVATOR DOOR CONTROL MECHANISM Harold Edward Galanty, Livingston, N. .L, assignor to Otis Elevator Company, New York, N. Y., a corporation of New Jersey Application November 13, 1952, Serial No. 320,267

13 Claims. (Cl. 187-48) This invention relates to mechanism for controlling the operation of power operated doors.

In modern elevator installations it is customary to provide power operated car and hoistway doors. Passenger elevators, and particularly those provided for intensive service, are often under the control of attendants who control closing of the doors and starting of the elevator car. The attendant is thus able to initiate door closing and consequent starting of the car as soon as there is no danger of a passenger being struck by the doors. This results in optimum service insofar as the car remains at a landing only long enough for the intending passengers to enter the car. At times, this type elevator may be automatically operated in which case the doors close automatically and starting of the car is in response to calls registered by intending passengers rather than under the control of an attendant. When arranged for such operation, the doors close automatically at the expiration of a door open time interval which, on the average, is of suflicient duration to permit intending passengers to enter the car. However, this interval is made as short as possible to insure a minimum amount of elevator standing time when service is demanded. Thus, a person may start to enter the car as the doors are closing or persons may be entering the car for a period of time greater than the normal door open time interval. In either instance if a person is proximate to the doors and is in danger of being struck thereby it is desirable to stop the closing movement of the doors. The doors may be reopened to their full open position or if they are in this position the door open time interval may be reestablished. According to the present invention, the detection of a person proximate to the doors is accomplished by a compensated electronic protective mechanism carried by the car door.

It is known that in an elevator installation structural conditions at the various landings are dilferent. When the car is at one landing the car door may be at a greater distance from the hoistway door than at another landing. Also at one landing the car door may be parallel to the hoistway door while at another landing the doors may not be parallel to each other. As a further variable condition, at one landing the car and the hoistway doors may move in unison whereas at another landing the car door may lead or lag the hoistway door as the doors are closing. Electronic protective mechanisms, which generally are responsive to the disturbance of an electric field caused by the proximity of a person to the mechanism, are adversely efiected by these variations. To effectively use such mechanism it has been necessary in the past to furnish additional means to provide a constant field around the mechanism to nullify the efiects of the above mentioned varying conditions. The present invention contemplates an improved electronic protective mechanism which compensates for field disturbances caused by the above conditions.

An object of this invention is to provide a protective mechanism which will detect the presence of a person when the person is about to enter, or is in the path of a power operated door and is proximate thereto.

Another object of this invention is to provide a protective mechanism of the above class which will permit the doors to closely approach passengers before it is actuated, thus resulting in a minimum number of reversal operations and a corresponding speeding of service.

It is a further object of this invention to provide protective mechanism of the above character which will be inconspicuous to the passengers and reliable in operation and which will involve a minimum amount of accessory equipment.

It is still another object of the invention to provide an electronic protective mechanism which is compact, can be mounted entirely on the elevator cab, and which is substantially unaffected by structural difierences that occur normally in the spacing of components at the various landings.

In carrying out the invention according to one preferred arrangement which will be described, a plurality of antennae are mounted along the leading edge of the car door, these being a relatively long signal antenna and two smaller compensating antennae. The antennae are shielded to provide shaped directional fields wherein they will be responsive to objects sought to be detected. In this manner the antennae are responsive to persons who may be in the path of and proximate to the car and the hoistway doors, but will not be responsive to persons inside the car who are near the car door. Each antenna is connected in the circuit of the control grid of an associated electron tube and is made a component of its gridcathode circuit. As the capacity to ground of an antenna varies, the impedance of the associated grid-cathode circuit varies, and a voltage source included in the circuit applies to the grid a voltage with respect to the cathode which is varied accordingly; that is, as the capacity to ground of the antenna increases, the voltage that is applied to the grid also increases. With all antennae equidistant from a grounded object, such as the door jamb, the protective mechanism circuits are arranged such that under this operating condition the output of the signal antenna branch of the device is balanced by the sum of the outputs of the compensating antennae branches. The signal antenna is located such that its capacity to ground is increased proportionally to a greater extent than is the capacity to ground of either compensating antenna when a foreign object such as a person moves into the path of and proximate to the doors. As a result, the output of the circuit branch associated with the signal antenna is no longer balanced by those of the branches associated with the compensating antennae and a net voltage output is obtained. This net voltage output is available for control operations and in the embodiment of the invention to be hereinafter described is used to control movement of the doors such that they may be arrested in closing or, if desired, arrested and returned to their open position.

Features and advantages of the invention will be apparent from the foregoing and from the following descriptions of several embodiments of the invention and the appended claims.

In the drawings:

Figure l is a somewhat simplified view in front elevation of an elevator car illustrating the door operating mechanism and the protective mechanism on the car door;

Figure 2 is a plan view of the car door and the hoistway door of Figure 1;

Figure 3 is an enlarged detail taken along line 3-3 of Figure 1;

Figure 4 is an enlarged detail taken along line 4 4 of Figure 1;

Figure is an enlarged detail taken along line 55 of Figure 3 showing an antenna unit;

Figure 6 is a simplified wiring diagram of the protective mechanism circuits;

Figure 7 is a simplified schematic wiring diagram of that portion of the elevator control circuits which relate to the control of the doors of the elevator installation;

Figure 8 is a key sheet for Figures 6 and 7 showing the electromagnetic switches in spindle form;

Figure 9 is a simplified wiring diagram of another arrangement of the protective mechanism circuits; and

Figure 10 is a simplified wiring diagram of still another arrangement of the protective mechanism circuits.

Referring to Figures 1 and 2, the elevator car 11 is illustrated as positioned at a landing 12. The car door 13 and the hoistway door 14 for that landing are illustrated in closed position. It is to be understood that the car door and hoistway doors may be operated in various ways, an arrangement being illustrated in which the doors are power opened and power closed. Single speed side opening doors have been shown although other type doors may be used with the invention. The car door is supported by door hanger rollers 15 which run on track 16. Although not shown in the drawings, the hoistway door is similarly supported.

The car door 13 and hoistway door 14 are operated by door engine 17. The door motor 18 drives shaft 20 through a gear reduction unit 21 to rotate arm 22 which is attached to plate 23 on the car door hanger 24 by link 25, connections 26 and 27 being pivotal. Clutch member 30 is rigidly attached to plate 23 and clutch member 31 is pivotally fastened to the plate by links 32. A roller 33 is rotatably connected to clutch member 31 and cam 34 is fixedly attached to track 16. When the door motor rotates arm 22 counterclockwise to open car door 13, clutch member 30, after taking up running clearances, engages roller 35 which is rotatably secured to the hoi" way door 14. Thus, both the car door and the hoistway door are opened together. As the doors continue to open, roller 33 on clutch member 31 rolls down the inclined surface 36 of cam 34 permitting member 31 to closely engage roller 35. Clutch member 31 is permitted to move until links 32 assume a horizontal position at which time further movement thereof is prevented by their engagement with bumper 37. The doors thus proceed to be fully opened, control of the motor speed, stopping and door checking being accomplished electrically by means of control switches in box 4%. The switches are cam operated, the cams being mounted on shaft 41 which is driven by chain 42 and sprocket 43 in accordance with door motion. To close the car door, door motor 18 is energized to rotate arm 2.2 clockwise. Clutch member 31, being in engagement with roller 35, closes the hoistway door. Clutch members 30 and 31 closely engage roller 35 until the doors are almost fully closed at which time roller 33 engages surface 36 of cam 34 to remove clutch member 31 from engagement with roller 35 to provide operating clearances between roller 35 on the hoistway door and the clutch members 30 and 31. Complete closing of the hoistway door is insured by a spring mounted in the hoistway which is placed in tension when the doors are opened. Spring 44 is tensioned when the car door is open and will close the car door at a slow speed if there is a failure of the power mechanism. Locking mechanism for the hoistway door is not shown in the drawings insofar as a description thereof will not aid in an understanding of the invention.

Referring now to Figures 2, 3, 4 and 5 the protective mechanism will be described. On the leading edge of the car door between the car door and the hoistway door is mounted a channel 45 running the full height of the car door. Channel 45 is secured to the door 13 at vertically spaced intervals by bolts 46. Angle brackets 47 are Weld ed to channel 45 at spaced intervals. The cover 50 which is of insulating material is secured to channel 45 and angle brackets 47 as by screws 51. The screws need not be insulated insofar as there is no potential applied to any of the metal members through which the screws pass. However, the screws securing cover 50 to the brackets 47 may be of insulating material similar to the cover so as to be inconspicuous to persons using the elevator car. With cover 50 in place, there is provided a box within which the detection equipment of the protective mechanism is located. The top and bottom of the unit formed by channel 45 and cover 50 are closed by plates 52 which may be welded to channel 45. There are three antenna units within the box, a large signal antenna unit 53 and two small compensating antenna units 54 and 55.

Reference will now be made to Figures 3, 4 and 5, which are views of the upper compensating antenna unit 54. All of the antennae units are similarly constructed except that the signal antenna unit is considerably longer than the compensating antenna units as is shown in Figure 2. The antenna 56 is mounted on spacers 57 of an insulating. material such as Lucite and secured thereto by screws 60. A shield 61 is provided for the antenna. The shield and antenna 56 are in the form of a box with the antenna forming one side thereof. Half hard aluminum has been found satisfactory as a material for the antenna and the shield. A nut and screw 62 are provided on the shield to facilitate making an electrical connection thereto. Also a nut and screw 63 are provided on the antenna in order to provide an electrical connection thereto. Shield 61 is mounted on wedge shaped blocks 64 of insulating material by screws 65 and these blocks in turn are secured to channel 45. The blocks are shaped so that the plane of the antenna 56 is at an angle, for example 45 degrees, with the plane of the car door. The antenna and shield arrangement thus provided has been found to produce a satisfactory antenna field pattern. Antenna 56 is susceptible to changes in its capacitive coupling to ground caused by objects in the path of the doors but shield 61 isolates the antenna from the immediately adjacent car door which is at ground potential. The antenna is also rendered unsusceptible to capacity changes due to the presence of persons within the car or to movement of the door operating equipment. A shielded electron tube 66 ismounted in a socket 67 on top of shield 61. The function of this tube and the reason for placing it directly on the shield 61 will be described hereafter as will the manner in which capacity changes operate the protective mechanism. The signal antenna unit 53 is located on channel 45 in a position for the signal antenna to scan a persons body as the person enters the car. The small compensating antenna unit 54 is located above signal antenna 53 on channel 45 near the top of door 13. Similarly, another small compensating antenna unit 55 is lo cated under signal antenna 53 on the channel near the bottom of the door. Figure 3 also shows resistor 68 mounted on channel 45. This resistor is the variable portion of resistor RP2 which is referred to in the description of the circuits which follows.

Reference will now be made to Figure 6. The compensating antennae are designated A1 and A3 and the signal antenna is designated A2. Antenna A1 is connected directly to the grid of triode tube TI. The anode circuit for the tube extends from B+ through a plate resistor RPI to the anode of the tube. From the cathode the circuit continues through cathode resistor RKI, paralleled by by-pass capacitor CKl, and thence to B0. Cathode resistor RKl is provided to furnish a grid bias for the tube, and capacitor CKI is provided to by-pass A. C. components of the load current. The grid input circuit runs from the antenna A1 to the parallel impedance of grid resistor RG1 and grid capacitor CGI to B0. An A. C. voltage source is connected from B0 to ground so that when considering the impedance from antenna to ground a complete loop circuit is encountered including a voltage source. In this circuit the grid of tube T1 is connected to a point between antenna A1 and the parallel impedance RG1 and capacitor CG1. It is thus apparent that the voltage impressed upon the grid of the tube with respect to B will be the voltage across the impedance formed by resistor RG1 and capacitor CG1. Capacitor CG1 is provided to by-pass high frequency noise so that spurious operation of the protective mechanism will not be had. Consider again the grid input circuit comprising the voltage source from ground to B0, the impedance formed by resistor RG1 and capacitor CG1 from B0 to antenna A1, and the impedance from antenna to ground. As the antenna to ground impedance varies, the voltage ratio between the RG1 and CG1 impedance and the antenna to ground impedance varies, and the voltage to the grid of the tube changes accordingly. When the antenna to ground impedance decreases, i. e. the antenna to ground capacity increases, the voltage across resistor RG1 and capacitor CG1 increases and the voltage to the grid of the tube, therefore, increases. There is a corresponding increase in the load current for the tube and an increased voltage drop across plate resistor RP1.

Antenna A3 and the tube T3 function in the same manner as antenna A1 and tube T1, the circuits associated therewith being similar. However cathode resistor RK3 comprises a fured resistor in series with a variable resistor for a reason which will be seen presently. Tube T3 is connected in parallel with tube T1 insofar as the plate resistor RP1 and the 13+ power supply are concerned. Hence the voltage drop across resistor RP1 is that due to the load currents of tube T1 and tube T3.

Antenna A2 is included in a similar circuit which forms the input circuit of tube T2. However, tube T2 is a twin triode as distinguished from the single triodes used for tubes T1 and T3. Resistors RKZ and RK2' and capacitors CKZ and CK2 are furnished to provide grid bias for each section of the tube. The connection from antenna A2 is to the grids of both sections as shown. The load current of each section of the tube is directed through plate resistor RP2 causing a voltage drop across the resistor. Resistor RP2 comprises a fixed resistor in series with a variable resistor for a reason which will be explained hereafter. Although a single section tube may be used, a twin triode has been resorted to because it facilitates balancing the output of tube T2 against the outputs of tubes T1 and T3.

It has been seen that the load currents of tubes T1 and T3 produce a voltage drop across resistor RP1 and that I the load currents of tube T2 produce a voltage drop across resistor RP2, and that each is effected by the change in the impedance to ground of the antenna for the respective tube. Wire W1 connected to the anodes of tubes T1 and T3 is at a potential above B0 equal to B+ minus the voltage drop across resistor RP1. anodes of tube T2 is at a potential above B0 equal to B+ minus the voltage drop across resistor RP2. If the voltage drops across resistors RP1 and RP2 are of the same magnitude and in phase, wires W1 and W2 are at the same voltage above B0 and there is no net output from the circuit system.

It has been stated that compensating antennae A1 and A3 are considerably smaller than signal antenna A2 and consequently the antenna to ground impedance of these antennae is greater than that of antenna A2. The values of resistors RG1 and RG3 and capacitors CG1 and CG3 are correspondingly increased above the values of resistor RG2 and capacitor CG2 so that the ratio of the impedance of antenna to ground to the impedance of the grid resistor in parallel with the grid capacitor is the same for each antenna and tube. In this manner voltages of equal magnitude are impressed upon the grids of the tubes as the antenna to ground impedance of each antenna is equally aifected as by each antenna being equidistant from ground. Also, with the grid capacitors and resistors selected as above mentioned, the voltages applied to the grids of the tubes, besides being of the same magnitude, will be in phase thus insuring that the current output from the tubes and the resulting voltage drops across the load resistors 0 Wire W2 connected to the 6- RP1 and RP2 will be in phase to facilitate balancing. Resistor RK3 which is a variable resistor is adjusted so that in the absence of a person proximate to the door there is no difference of voltage between wires W1 and W2. With an A. C. voltage from B0 to ground and with the antenna to ground impedance of each antenna equally affected as by the proximity of the antennae to a flat surface as door jamb 70 (Figure l), resistor RP2 is adjusted so that there is again no net output voltage between wires W1 and W2. The system just described will then compensate automatically for antenna to ground impedance changes resulting as the antennae move relative to a flat surface which affects all antennae equally. Although the protective mechanism is here described as used in conjunction with a door system in which the car door is connected to the hoistway door during operation thereof it is particularly applicable to systems in which the doors are operated separately. The fact that the car door sometimes leads and sometimes lags the hoistway door is immaterial because in either event the hoistway door, being a flat surface, is an object which effects all antennae equally. Hence if the capacity of hoistway door to signal antenna increases to raise the output of tube T2, the capacity of hoistway door to the compensating antennae is likewise increased to raise the output of tube T1 and tube T3. Similarly, if the antenna to ground capacity for one antenna decreases, it decreases for all antennae, thus the net output voltage remains zero or approximately zero as the elevator doors move from an open to a closed position as long as the movement is relative to a flat surface which is equi-distant from all antennae. However, if an irregularly shaped object such as a persons body is placed in the path of the doors and proximate thereto a different result obtains. The large mass of the person is nearer to the large signal antenna A2 than to the small compensating antennae A1 and A3 and consequently the antenna to ground impedance for the signal antenna A2 is decreased proportionally more than the antenna to ground impedance for the compensating antennae A1 and A3. The signal antenna A2 can therefore be considered an object detecting antenna. The previous balance in the circuits has now been destroyed and a larger signal voltage is im pressed on the grids of tube T2 than on the grids of tubes T1 and T3. There is, consequently, a net voltage difference between wires W1 and W2 which is applied to full wave rectifier 71. The output of the rectifier is smoothed by filter 72 and then fed to sensitive relay S0 to cause reopening of the elevator doors. Such an operation will be described hereafter.

In order to minimize the possibility of noise pick-up in the amplifier stage two conductor leads are used for the anode and cathode leads to the tubes. Also, to limit the length of the leads leading from the antennae to the grids of the tubes and to minimize noise pick-up in the input stage, the tubes are mounted on the antennae shields as heretofore mentioned.

The reason for using two compensating antennae is that in elevator systems the hoistway doors and the car doors are frequently not parallel. Non-parallelism of the doors may be due to unbalanced loading of the elevator car platform in which case rotation of the car frame will take place around an axis between the upper and lower car guiding means. If such were the case and only one compensating antenna was used, the adjustment giving Zero output at a floor where the doors are parallel would result in there being a net output at floors where the doors are not parallel. With two compensating antennae, one at the top of the car door and one near the bottom thereof the total output of the two tubes associated therewith will remain substantially constant whether or not the doors are parallel. The antenna to ground impedance of the compensating antenna farther away from the hoistway door will be increased with a corresponding decrease in the output of the tube associated therewith, but the antenna to ground impedance of the compensating antenna nearer the hoistway door will be decreased with a corresponding increase in the output of the associated tube.

Reference will now be made to Figure 7 which diagrammatically illustrates the circuits for controlling the door motor 18. The circuits are shown in straight or across-the-line form in which the coils and contacts of the various switches are separated in such manner as to render the circuits as simple and direct as possible. The relationship of the coils and contacts may be seen from Figure 8 where the switches are arranged in alphabetical order and shown in spindle form. The coils and contacts in the wiring diagram are in horizontal alignment with the corresponding coils and contacts on the spindles. Inasmuch as the invention is not limited to any particular type of elevator control system, a complete elevator control system has not been shown. The circuits have been considerably simplified and it is to be understood that many modifications might be made thereto to provide suitable door operation in a given installation and to adapt them to complete control systems.

The electromagnetic switches employed in the circuits shown in Figure 7 are designated as follows:

DC-Door close switch.

DD-First slowdown switch.

DDC-Second slowdown switchclosing. DDO-Second slowdown switch-opening.

D-Door open switch.

DTDoor reversal time switch.

H-Field and brake switch (only the contacts are shown). NT-Hall time switch.

S0-Protective mechanism relay (see Figure 6).

Throughout the description which follows, these letters will be applied to the coils of the above designated switches. Also, with reference numerals appended thereto, they will be applied to the contacts of these switches. The electromagnetic switches are illustrated in deenergized condition.

The door operating circuits are illustrated as being supplied with direct current from rectifier RF which is connected to three phase alternating current lines L1, L2 and L3. The door motor armature is designated DMA and its field winding is designated DMF. Resistors RDM are speed control resistors for door motor 18. EDB is a rectifier which serves to dynamically brake the door operating motor to bring it to a stop upon operation of the protective mechanism. DOL1, DOL2, DOL3, DCLl, DCL2, DCL3 are limit switch contacts operated by the door motor. These are in box 4-0, Figure 2, as previously indicated. Resistors RDT and RDTl and capacitor CDT control the timing of switch DT. Resistor RNT and capacitor CNT control the timing of switch NT.

The manner in which the doors are controlled may vary considerably, depending upon the characteristics of the particular installation. In the circuits illustrated the doors open automatically as a stop is made at a landing and close automatically at the expiration of a time interval. That this may be understood assume that the elevator is approaching a landing at which a stop is to be made. While the car is running, field and brake switch H is energized. As the car arrives at the landing at which the stop is being made, switch H drops out and in so doing separates contacts H3 and engages contacts H1 and H2. The separation of contacts H3 disconnects coil NT from the supply line but the relay does not drop out immediately, it being maintained in operative condition by the discharge of condenser CNT. The engagement of contacts H2 and the maintenance of contacts NT1 in engagement completes a circuit for coil D0 by way of contacts DZ and DOL3. Contacts DZ are engaged when the car is stopped in a door zone at a landing and contacts DOL3 are engaged while the doors are closed. Energization of coil D0 causes contacts D01, D02, D03, D04 and D06 to engage and contacts D05 to separate. Contacts D06 reconnect coil NT to the supply lines and contacts D04 complete a circuit for coil DD through limit switch contacts DOLI. Switch DD then engages contacts DD1 and DD4 and separates contacts DD2 and DD3. A circuit for coil DDO is completed through limit switch contacts DOL2 to separate contacts DD01. A circuit for the door motor armature DMA can now be traced from line 51 through a portion of resistance RDM2, contacts DD1, contacts DT1, contacts D03, armature DMA, reactor XL and contacts D01 to line S2. As the doors approach a posiiton about half way open, limit switch contacts DOL1 open to disconnect coil DD from the supply lines. As a result contacts DD1 and DD4 are separated and contacts DD2 and DD3 engage. Separation of contacts DD1 places all of resistance RDM2 in series with armature DMA and engagement of contacts DD2 inserts resistor RDM3 in parallel with the armature and reactor XL, the parallel circuit being made through contacts D02, contacts DD2 and resistor RDM3. The manipulation of the resistors as described results in the first step of slowdown in the door opening operation. Further movement of the doors to full open position affects opening of limit switch contacts DOL2 to disconnect coil DDO from the supply lines. Thus contacts DD01 are engaged when the doors are approximately two to four inches from full open position. A second step of slowdown occurs when a portion of resistor RDM3 in parallel with armature DMA is shorted out. The doors then move at a slow speed to full open position where limit switch contacts DOL3 are separated to disconnect coil D0 from the supply lines. Contacts D01, D02, D03, D04 and D06 separate and contacts D05 engage, contacts D03 and D01 causing the door motor armature to be disconnected from lines S1 and S2. Separation of contacts D06 removes coil NT from the supply lines but the relay does not drop out immediately due to the discharge of condenser CNT.

A door closing operation will now be described, and insofar as functioning of the protective mechanism will occur during such an operation, the operation to be described will include a reversal due to the protective mechanism detecting a person in the path of the doors. Reference will be made to Figure 6 where the protective mechanism circuits are described.

With the doors fully opened, limit switch contacts DCLl, DCL2 and DCL3 are engaged. After the expiration of hall time, relay NT drops out, separating contacts NTI and engaging contacts NT2. Engagement of contacts NT2 completes a circuit for coil DC through contacts D05 and DCL3. Contacts DCI, DC2, DC4 and DC5 are then engaged and contacts D03 separate. Coil DDC is connected across the supply lines by contact DCL2 causing contacts DDCI, DDCZ and DDC4 to be engaged and contacts DDC3 to be separated. A circuit for coil DT is completed by contacts DC5 and DDC4. Energization of coil DT separates contacts DT1 and engages contacts DT2. A circuit for coil DD is then completed through contacts DT2 and DCL1. Contacts DD1 and DD4 are then engaged and contacts DD2 and DD3 are separated. The door motor armature DMA is connected to' the" supply lines S1 and S2 to cause the doors to be closed through a portion of resistor RDM2, contacts DD1, contacts DDCl, a portion of resistor RDMl, contacts D01, reactor XL, armature DMA and contacts DC4. A circuit in parallel with armature DMA and reactor )& can be traced through contacts DC2 and resistor RDM4. If, while the doors are closing under these conditions, a person enters into a position proximate to the doors a reversal of door travel will take place under the influence of the protective mechanism. Due to the location of the antennae most of the persons body will be nearer to the large signal antenna A2 than to the small compensating antennae at the top and bottom of the doors. This results in the antenna to ground impedance for antenna A2 being decreased proportionally more than that for the compensating antennae A1 and A3. Consequently, the voltage applied to the grids of tube T2 with respect to the cathode thereof will be greater than the voltages applied to the grids of tubes T1 and T3. There is a corresponding increase in the load currents of tube T2 and in the voltage drop across resistor RPZ, it being greater than the voltage drop across resistor RPl due to the load currents of tubes T1 and T3. Thus the potential on wire W1 exceeds that on wire W2 by an amount sufficient to operate sensitive relay SO. Energization of coil SO engages contacts S01 which completes a circuit to energize coil NT. Coil SO remains energized as long as there is a difference in potential on wires W1 and W2 due to the presence of a person in the path of the doors. When switch NT operates it engages contacts NT1 and separates contacts NT2. Separation of contacts NT2 disconnects coil DC from the line and thus causes separation of contacts DC1 and DC4 to disconnect armature DMA from the lines to stop closing travel of the doors. To aid in bringing the armature to a halt, it is dynamically braked by providing a short circuit path around the armature through rectifier EDB, contacts DDC2 and contacts DC3. Separation of contacts DCS deenergizes coil DT but the relay does not release immediately due to the discharge of capacitor CDT through the coil. Engagement of contacts NT1 connects coil DO across the line, the circuit being traced from line S1, contacts DOLL, which were closed when the doors moved from their full open position, contacts H2, contacts NT1, contacts D2, coil D to line S2. Energization of coil DO results in opening of the car door as above described. However, due to the opening resulting from a reversal a few slight modifications occur. Insofar as relay DT did not fall out, contacts DTI remained separated, inserting resistor RDMS in series with the armature DMA. Resistor RDMS insures that a low voltage is applied to the armature DMA during a reversal. If the speed of the rotor in closing just prior to reversal had been low enough as by switch DD dropping out when contacts DCLl separated, switch DT would have fallen out immediately rather than be delayed by the discharge of condenser CDT and resistor RDMS would not be inserted in series with armature DMA. After the doors reach their fully open position they remain therein until the expiration of hall time which is measured from the time the doors reach full open position or from when there is no person in the path of the doors to effect operation of the protective mechanism relay SO, whichever event occurs latest. When switch NT drops out contacts NT1 separate and contacts NT2 engage. Limit switch contacts DCLl, DCLZ and DCL3 are engaged. Energization of coil DC engages contacts DCl, DC2, DC4 and DC5 and separates contacts DC3. Coil DDC is connected across the line by contacts DCLZ thereby engaging contacts DDCl, DDC2 and DDC4 and separating contacts DDC3. A circuit for coil DT is completed by contacts DC5 and DDC4 to engage contacts DTZ and separate contacts DTl. Coil DD is energized through a circuit from line S1, contacts DTZ, contacts DCLl, coil DD to line S2. As a result, contacts DD1 and DD4 are engaged and contacts DB2 and DD3 are separated. A circuit for armature DMA can be traced from line S1, a portion of resistor RDM2, contacts DD1, contacts DDCI, a portion of resistor RDMl, contacts DCl, reactor XL, armature DMA, contacts DC4 to line S2. Resistance is placed in parallel with the armature so that the doors close at a slower speed than that at which they open. This circuit includes resistor RDM4 and contact DC2. The doors will commence to close at a speed regulated by the series and parallel resistance until they reach a position aproximately midway closed when limit switch contacts DCLl separate to initiate slowdown, separation of contacts DD1 inserting all of resistor RDMZ in series with the armature DMA and engagement of contacts DD3 short circuiting a portion of resistor RDM4 in a parallel circuit around the armature. The second step of slowdown occurs when the doors are approximately two to four inches from the full closed position at which id time contacts DCLZ are opened to deenergize coil DDC thus engaging contacts DDC3 and separating contacts DDCl, DDC2 and DDC4. Contacts DDCl increase the amount of armature series resistance and contacts DDC3 decrease the amount of resistance in parallel with the armature to decrease the speed of the doors to a very low value. When the doors are fully closed, contacts DCL3 open to deenergize coil DC to disconnect armature DMA from across the line. Reactor XL is provided in series with the door motor armature to smooth the transition from one motor speed to another as the various switching operations take place.

Reference will now be made to Figure 9 which shows another arrangement of the protective mechanism circuits. As before, the sum of the antenna to ground impedance for the compensating antennae A1 and A3 is compared with that of the signal antenna A2, but a different means for so doing is utilized. Here the antennae are connected to the grids of electron tubes which are wired in cathode follower circuits. Transformers are used in the cathode follower output circuits in order that no direct current voltage from the B+ power supply be impressed on the circuits which follow. A capacitor is con nected in series with the primary winding of each transformer to prevent saturation thereof with consequent nonlinear operation. The sum of the A. C. voltages from the transformers TRI and TR3 for the compensating antennae is connected across a diode tube D1 in series with a capacitor C1, thus the voltage on the capacitor is equal to the peak voltage of the transformers for the compensating antennae. Resistor R1 is parallel with capacitor C1 furnishes a discharge path for the capacitor charge. In the case of an electrolytic capacitor the discharge path may be the leakage resistance of the capacitor. The time constant of the discharge circuit is made comparatively short so that the peak voltage on the capacitor C1 may readily follow the peak voltage of the transformers for the compensating antennae. However, the time constant may not be too small for a reason which will soon be apparent.

The A. C. voltage from the transformer TR2 for the signal antenna A2 is connected across a diode tube D2 which is biased by voltage on the capacitor C1 due to the voltage from the transformers TRl and TR2. The output from transformer TR2 is varied by adjusting the tap of cathode resistance RK2 across which the transformer is excited. With no object in the path of the car and the hoistway doors the tap of resistance RK2 is adjusted so that the sum of the voltage output from transformers TRI and TR3 is equal to that of transformer TR2. Consequently the voltage impressed on tube D2 is equal to the voltage on capacitor C1 from transformers TRl and TR3 and there is no signal transmitted to amplifier tube AT. If the output voltage from transformer TR2 lagged in phase behind that of transformers TRl and TR3 clue to the circuit parameters in the cathode follower circuits it would be difiicult to obtain a balance between the two voltages and to avoid impressing a signal on the grid of tube AT. To compensate for the phase lag, the capacitor voltage is maintained for a short interval by the discharge circuit. However, if the voltage output from transformer TR2 exceeds that of transformers TRl and TR3 due to the presence of a person in the path of the doors, the voltage of tube D2 exceeds that of capacitor C1 and there is a resultant signal which is impressed on the grid of amplifier tube AT. The cathode followers have an amplification factor of less than unity and, therefore, amplifier tube AT is used to obtain a signal of suitable magnitude for operating relay tube RT. When tube RT is fired, relay SO operates to engage contacts S01 to cause reopening of the doors as above described. In this arrangement additional contacts S02 on relay SO operate relay SOX, the purpose of which is to short out tube RT and prepare the circuits for another operation.

In the arrangement shown in Figure 9, there is the possibility that if the antenna to ground impedance of a compensating antenna is decreased as by a person plac ing his hand near the compensating antenna, the circuits may not function to reopen the doors. Ordinarily this condition is avoided by the location of the compensating antennae in positions where such placing of a persons hand is extremely unlikely. However, the arrangement shown in Figure avoids this difiiculty. That is, even if the person places his hand near the compensating antenna, the doors will be reopened; This circuit arrangement is similar to that shown in Figure 9', in that cathode follower circuits are used, but instead of utilizing a single pair of diodes, one biasing the other, the arrangement shown in Figure 10 uses two pair of diodes. Referring more specifically to Figure 10, the sum of the output voltages of transformers TR1 and TR3 is impressed on the diode tubes D1 and D3. The output voltage of transformer TRZ is impressed on diode tubes D2 and D4. As in the arrangement of Figure 9, the voltage impressed on tube D1 charges capacitor C1 to a voltage of the same value, thus biasing diode D2. In addition though, the voltage impressed on tube D4 charges capacitor C2 to a voltage of the same value to bias diode D3. When balanced conditions prevail, there is no signal impressed on the grid of amplifier tube AT, but when the antenna to ground impedance of the signal antenna A2 is decreased as by the presence of a person in the path of the doors the voltage impressed on diode D2 exceeds that on capacitor C1 to cause reopening of the closing doors. On the other hand, if a person places his hand near one of the compensating antennae, say antenna Al, the antenna to ground impedance therefor decreases and the voltage impressed on tube D3 exceeds the voltage on capacitor C2 to again cause operation of the doors.

While the invention has been described in conjunction with a side opening single speed door, movement of which is controlled electrically, it is to be understood that the invention can be applied to other type doors and to other type door controls. The invention is particularly applicable to doors in which the car door and the hoistway door are controlled by separate means, or are operated in such a way that the doors are not mechanically coupled during a door operation.

Although the invention has been described as applied to an elevator control system in which both the starting and stopping of the elevator car are under the control of the passengers themselves, it is also applicable to other control systems, especially those in which the starting of the car is automatic and in which the doors are closed automatically. While the circuits are arranged to affect the reopening of the doors by the protective mechanism, they may be arranged simply to bring the doors to a stop. Also, the door open time interval after a protective mechanism operation may be made shorter than that after a normal door opening operation.

The construction of the protective mechanism and the protective mechanism circuits themselves are subject to considerable variation. Whilea number of circuit arrangements have been illustrated it is to be understood that other circuits may be utilized. Similarly, many different antennae arrangements can be provided as can many different antenna shapes. By foregoing consideration of nonparallel car and hoistway doors, a single compensating antenna may be used rather than two compen sating antennae as disclosed in the preferred arrange ment of the protective device described.

Thus, as many changes could be made in the above construction and many apparently Widely diiferent embodiments of this invention could be made without dea plurality of landings and in which closure means control access to said elevator car at a landing, detecting means carried by said closure means for detecting the presence of objects foreign to said elevator system in a zone proximate to said closure means, and compensating means carried by the closure responsive to objects of said elevator system proximate to said detecting means for compensating for the action of said detecting means to prevent the detection of such objects of said elevator system.

2. In an elevator system in which an elevator car serves a plurality of landings and in which power closure means control access to said elevator car at a landing, an object detecting means carried by said closure means, a compensating means carried by said closure means, and additional means for controlling said closure means, said additional means being inoperative when said object detecting means and said compensating means are balanced in the absence of an object foreign to said elevator system proximate to said closure means but being responsive to an unbalance of said object detecting means and said compensating means due to the presence of a foreign object proximate to said closure means.

3. In an elevator system in which an elevator car hav ing a car door serves a plurality of landings provided with hoistway doors controlling access to said car, power mechanism for operating said car door and a hoistway door at a landing at which said car is stopped, an antenna carried by said car door, means responsive to a change in antenna to ground impedance when a person moves into the path of said doors to control said power mechanism to stop the closing of said doors, and means carried by said car door to prevent said first mentioned means responding to a change in antenna to ground impedance when said change is due only to the relative movement of said antenna and elements of said elevator system.

4. In an elevator system in which an elevator car serves a plurality of landings and in which closure means controls access to said elevator car at a landing, power mechanism for said closure means, two antenna systems carried by said closure means, each having means for producing an output signal, the output signals of said systems being balanced when no object foreign to said elevator system is proximate to said closure means, the output signals of said systems being unbalanced when a foreign object is proximate to said closure means, and means subject to the unbalance of said output signals for controlling said power mechanism to stop the closing movement of said closure means.

5. In an elevator system in which an elevator car serves a plurality of landings and in which closure means controls access to said elevator car at a landing, power mechanism for operating said closure means, two antenna systems carried by said closure means, each having means for producing an output signal controlled by the impedance of the antenna system to ground, means for comparing said output signals, and means responsive to a predetermined difference in said output signals caused by a change in said impedances to ground due to the proximity of a person to said closure means for controlling said power mechanism to stop the closing of said closure means.

6. In an elevator system in which an elevator car serves a plurality of landings and in which closure means controls access to said elevator car at a landing, power mechanism for operating said closure means, two antenna systems carried by said closure means, each having means for producing an output signal controlled by the impedance of the antenna system to ground, means for comparing said output signals by combining them to derive a difference product, and means responsive to said diiference product caused by a change in said impedances to ground due to a person moving into the path of said closure means in closing for controlling said power mechanism to stop the closing of said closure means.

7. In an elevator system in which an elevator car serves a plurality of landings and in which closure means controls access to said elevator car at a landing, power mechanism for said closure means, a plurality of electron tubes connected in two circuit groups, means carried by said closure means for applying a varying voltage to said tubes so that the voltage outputs of said circuit groups are balanced when no object foreign to said elevator system is proximate to said closure means, said means applying a dilferent varying voltage to said tubes when a foreign object is proximate to said closure means so that the voltage output of one of said circuit groups exceeds that of the other of said circuit groups, and additional means responsive to the unbalance of said voltage outputs to control said power mechanism.

8. In an elevator system in which an elevator car serves a plurality of landings and in which closure means controls access to said elevator car at a landing, a signal source, an object detecting means carried by said closure means for receiving a signal from said source, compensating means carried by said closure means for receiving a signal from said source, said signal to said object detecting means being increased more than that to said compensating means as an object foreign to said elevator system moves into a position proximate to said closure means, and means responsive when said signal to said object detecting means exceeds that to said compensating means to control said closure means.

9. In an elevator system in which an elevator car serves a plurality of landings and in which closure means controls access to said elevator car at a landing, a first group of variable impedance circuits, a second group of variable impedance circuits, a first means responsive to changes in the impedance of said first group of circuits, a second means responsive to changes in the impedance of said second group of circuits, said first and said second means being balanced when the impedances of said circuits are changed proportionally by movement of said closure means relative to flat surfaced elements of said elevator system, said first and said second means being unbalanced when the impedances of said circuits are changed disproportionally by movement of an object foreign to said elevator system into a position proximate to said closure means, and additional means responsive to the unbalance of said first and said second means to control said closure means.

10. In an elevator system in which an elevator car having a car door serves a plurality of landings provided with hoistway doors controlling access to said car, power mechanism for operating said car door and a hoistway door at a landing at which said car is stopped, an antenna carried by said car door, an electron tube having a control grid, an anode and a cathode, said grid being connected to said antenna, means for applying a voltage to said grid with respect to said cathode proportional to the antenna to ground impedance, said voltage being increased as said impedance decreases, a second and a third antenna carried by said car door, a second and a third electron tube, each having a control grid, an anode and a cathode, each of said grids being connected respectively to said second and third antenna, means for applying a voltage to said grids with respect to said cathodes proportional to the antenna to ground impedance for each antenna, said voltage being increased as said impedance decreases, and additional means balancing the output currents of said second and said third tubes with that of said electron tube when the antennae to ground impedances are affected only by elements of said elevator system.

11. In an elevator system in which an elevator car having a car door serves a plurality of landings provided with hoistway doors controlling access to said car, power mechanism for operating said car door and a hoistway 14 door at a landing at which said car is stopped, an antenna carried by said car door, an electron tube having a control grid to which said antenna is connected, an anode and a cathode, means for applying a voltage to said grid with respect to said cathode which is proportional to the antenna to ground capacity, a second antenna carried by said car door, a second electron tube having a control grid to which said antenna is connected, an anode and a cathode, means for applying a voltage to said grid with respect to said cathode for said second tube which is proportional to the second antenna to ground capacity, and means responsive to a predetermined difference in the output currents of said tubes, there being a difference of current exceeding said predetermined difference when a person moves into the path of and proximate to said doors, said means controlling said power mechanism to stop movement of said doors toward a closed position.

12. In an elevator system in which an elevator car having a car door serves a plurality of landings provided with hoistway doors controlling access to said car, power mechanism for operating said car door and a hoistway door at a landing at which said car is stopped, a first antenna mounted along the leading edge of the car door, an electron tube having a grid to which said antenna is connected, an anode and a cathode, a second antenna mounted along the leading edge of the car door above said first antenna and connected to the grid of a second electron tube, also having a cathode and an anode, a third antenna mounted along the leading edge of the car door below said first antenna and connected to the grid of a third electron tube also having a cathode and an anode, means for applying a voltage to the grids of said tubes with respect to their cathodes which is proportional to the antenna to ground impedances of said antennae for said grids respectively, and means responsive when a person enters a zone proximate to said first antenna changing the antenna to ground impedance for said antenna to a greater extent than changing the antenna to ground impedances for said second and third antennae to control said power mechanism to stop the closing movement of said doors.

13. In an elevator system in which an elevator car having a car door serves a plurality of landings provided with hoistway doors controlling access to said car, power mechanism for operating said car door and a hoistway door at a landing at which said car is stopped, a first antenna mounted along the leading edge of the car door, an electron tube having an anode, a cathode, and a grid to which said antenna is connected, an alternating voltage source for impressing a voltage on said grid with respect to said cathode which varies in magnitude as the antenna to ground impedance for said antenna varies, compensating antennae mounted along the leading edge of the car door, one above and one below said first antenna, an electron tube for each of said compensating antennae having an anode, a cathode, and a grid to which each antenna is connected, an alternating voltage source for impressing a voltage on the grids with respect to the cathodes which varies in magnitude as the antenna to ground impedance for said compensating antennae varies, means for balancing the output of said tube for said first antenna with that of said tubes for said compensating antennae when the antenna to ground impedances for all antennae are varied proportionally, and means responsive when the output of said tube for said first antenna exceeds that of said tubes for said compensating antennae to control said power mechanism to regulate movement of said doors.

References Cited in the file of this patent UNITED STATES PATENTS 2,634,828 Bruns et al. Apr. 14, 1953 

